"Sin is what you do when your heart is not satisfied with God. No one sins out of duty. We sin because it holds out some promise of happiness."
- John Piper

"What is sin?
It is the glory of God not honored.
The holiness of God not reverenced.
The greatness of God not admired.
The power of God not praised.
The truth of God not sought.
The wisdom of God not esteemed.
The beauty of God not treasured.
The goodness of God not savored.
The faithfulness of God not trusted.
The commandments of God not obeyed.
The justice of God not respected.
The wrath of God not feared.
The grace of God not cherished.
The presence of God not prized.
The person of God not loved.
That is sin."
- John Piper

"Even so far today I've heard one preacher who says, 'We do not speak about sin in our church.' Then I can tell him that the Holy Spirit of God does not work in his church nor in his ministry. Why? Because one of the principle ministries of the Holy Spirit is to convict the world of sin so if you do not talk much about sin, count on it, the Holy Spirit is not much in your ministry."
- Paul Washer